Internal combustion engines, including diesel engines, gasoline engines, natural gas engines, and other engines known in the art, may exhaust a complex mixture of air pollutants. The air pollutants may be composed of gaseous compounds and solid particulate matter, which may include unburned carbon particles called soot.
Due to increased attention on the environment, exhaust emission standards have become more stringent. The amount of particulates emitted from an engine may be regulated depending on the type of engine, size of engine, and/or class of engine. One method that has been implemented by engine manufacturers to comply with the regulation of particulate matter exhausted to the environment has been to remove the particulate matter from the exhaust flow of an engine using a particulate trap. A particulate trap is a filter designed to trap particulate matter in, for example, a wire mesh filtering media. Using the particulate trap for extended periods of time may enable the particulate matter to accumulate in the wire mesh filtering media, thereby reducing filter functionality and engine performance.
Various regeneration techniques may be employed to combat the effects of accumulating particulate matter. For example, U.S. Pat. No. 5,009,065 (the '065 patent) issued to Howe et al. on Apr. 23, 1991, describes using an exhaust processor to filter particulate matter from a combustion product. The exhaust processor of the '065 patent is designed for use in a diesel engine and includes a primary substrate and an auxiliary substrate for removing the particulate matter from an exhaust flow. During normal exhaust processor operation, exhaust flow is directed into a first region containing the primary substrate. During regeneration, a valve pivotally coupled to a processor housing is moved from a first position, where the exhaust flows into the first region, to a second position, where the exhaust is blocked from the first region and allowed to flow through a second region having the auxiliary substrate. The pivotally coupled valve is moved from the first position to the second position by a dedicated actuator. A burner is activated to heat the substrate and oxidize trapped particulate matter, thereby regenerating the substrate. After regeneration is complete, the pivot valve is returned to the first position. The '065 patent also describes an alternate embodiment that includes a slideably movable valve for diverting exhaust flow from the primary substrate to the auxiliary substrate and vice versa.
Although the exhaust processor of the '065 patent may reduce the particulate matter exhausted to the environment and reduce the buildup of particulate matter in the exhaust processor, the exhaust processor may be large and costly. For example, in order to prevent excessive backpressure within an engine system coupled to the exhaust processor, both the primary and auxiliary regions of the exhaust processor must be sufficiently large to handle the entire exhaust flow. This size requirement increases the cost of the exhaust processor. In addition, both the pivot valve and the slidably movable valve are configured to block only two substrates, making the exhaust processor of the '065 patent expansion-limited.
The disclosed particulate trap is directed to overcoming one or more of the problems set forth above.